Desiccant air dryer

ABSTRACT

METHOD AND APPARATUS FOR THE PRACTICE THEREOF, AT DEHYDRATING HOT, PRESSURED GAS, IN WHICH A MINOR PORTION OF THE PRESSURED GAS TO BE DEHYDRATED IS CONDUCTED THROUGH ONE OF A PAIR OF DEHYDRATING DESICANT CHAMBERS, TO REACTIVATE THE LATTER, WHILE THE MAJOR PORTION OF THE GAS IS CONDUCT THROUGH THE OTHER CHAMBER OF THE PAIR, TO DEHYDRATE SAID MAJOR PORTION.

March 9, 1971 w, M, DYNES 3,568,406

DESICCANT AIR DRYER Filed 001?. 28, 1968 INVENTOR W551. EY M. DYNES United States Patent 3,568,406 DESICCANT AIR DRYER Wesley M. Dynes, Hickling Heights, Corning, N.Y., assignor to Iugersoll-Rand Company, New York, N.Y. Filed Oct. 28, 1968, Ser. No. 771,112 Int. Cl. B01d 53/04 US. C]. 55-33 11 Claims ABSTRACT OF THE DISCLOSURE Method, and apparatus for the practice thereof, of dehydrating hot, pressured gas, in which a minor portion of the pressured gas to be dehydrated is conducted through one of a pair of dehydrating desiccant chambers, to reactivate the latter, while the major portion of the gas is conducted through the other chamber of the pair, to dehydrate said major portion.

This invention pertains to gas dehydrating methods, and to apparatus for the practice of such methods, and in particular to dehydrating methods for hot, pressured gas, and apparatus, in which a portion of the very gas to be dehydrated is employed to reactivate the means which are used for extracting the aqueous constituents.

In the prior art types of gas dehydrating methods and apparatus, it is commonly known to employ electrical, steam, or other extraneous sources of what I will call commercial energy, or water or refrigerant coolers, to reactivate the dehydrating apparatus. Thus, the embedding of electrical heaters in the desiccant chambers, the introduction of steam thereto, or like methods, are practiced as means for driving otf-i.e., separatingthe aqueous constituents from the usual chemical desiccant.

The prior art types noted are uneconomical; they require the arrangement for, and coupling and control of the extraneous energy source. Further, the energy used is Wholly dissipated in the reactivation process. Additionally, the deployment of other energy sources, in the dehydration of gas and the reactivation of the dehydration means, compounds the maintenance problems and the system failure rate. Failure or malfunctioning of the ancillary electrical subsystem, or the extraneous steam subsystem, will disable the overall gas dehydrating apparatus even though the supply, piping, and control of pressured gas to be treated is without fault.

More eflicient, more economical, less given to failure and maintenance difliculties, would be a gas dehydrating method, and apparatus for its practice, in which no ancillary commercial energy source is required. Accordingly, it is an object of this invention to teach a gas dehydration method, and apparatus for the practice thereof, in which no ancillary energy source is required for the reactivation of the dehydrating deviceother than that of power-moved ambient atmosphere, and the means for its movement. It is another object of this invention to teach a gas dehydration method and apparatus in which the hot pressured gas to be treatedtogether with the ambient atmosphereis the energy medium employed for reactivation of the dehydrating devices.

A feature of this invention, both in the method and apparatus taught hereby, comprises the provisioning of both primary and secondary pressured gas inlet and outlet means for the dehydrating devices or means for extracting the aqueous constituents-i.e., the desiccant chambers, in which the secondary means are throughconnected with the primary inlet means. Thus, a minor portion of the tobe-processed pressured gas is passed through one of the extracting means while the major portion of the gas is conducted through the other, or another, of the extracting means. This practice, and the apparatus taught herein,

causes the process gas, i.e., the gas to-be-processed, to reactivate the one aqueous extractor, while the major stream of the gas is being dehydrated by the other (or another) aqueous extractor. Further, the throughconnection of the secondary outlet means with the primary inlet means returns the reactivating minor portion of the gas to the major stream of process gas for its own dehydration.

Further objects and features of this invention will become more apparent by reference to the following discussion taken in conjunction with the accompanying figure. The figure is a schematic diagram of one embodiment of the invention shown in cooperative association with a gas compressor.

As the diagrammatic figure shows, a plurality of aqueous extractors, or desiccant chambers 10 and 12 are coupled to the output 14 of a gas compressor 16. The teaching of my invention can be practiced with any number of chambers. That is to say that a single desiccant chamber can be used, but in such a circumstance, this type of system would have intermittent use. It could dehydrate for only a given period of time, and then it would have to be switched to reactivation. Any plurality of chambers, however, providing that the chamber flow rates and the gas source rates are complementary, will provide continuous dehydration.

Chamber 10 has primary pressured gas inlet and outlet means 18 and 20, respectively, and chamber 12 has primary pressured gas inlet and outlet means 22 and 24, respectively. Inlet means 18 and 22 are commonly throughconnected with system inlet line 26, and outlet means 20 and 24 are commonly throughconnected with system outlet line 28. Chambers 10 and 12 also have secondary pressured gas inlet and outlet means, these inlet means being 30 and 32, and these outlet means being 34 and 36, respectively. All of these several inlet and outlet means, of course, comprise conduits, piping, or the like.

Chambers 10 and 12 confine therewithin a desiccant medium 38, such as silica gel, or the like, for extracting from gas conducted therethrough the aqueous constituents thereof. Embedded in the desiccant medium 38, and throughconnected with the secondary inlet and outlet means 30 and 34, and 32 and 36, are heat exchanger devices 40. Devices 40 have openings only at the ends thereof, where they throughconnectedly couple with means 30, 32, 34, and 36, to insure the confinement of gas therewithin and to provide for the subsequent reclamation of the gas submitted therethrough. Further, secondary inlet means 30 and 32 are commonly throughconnected with inlet line 26, at a first location 42, and secondary outlet means 34 and 36 are also commonly throughconnected with inlet line 26, at a second location 44. By this arrangement, by this teaching of my method, a minor portion of the hot, pressured gas to be processed can be conducted from the primary inlet line 26, through the devices 40, and returned to the line 26. Location 42 comprises an orificed coupling for admitting a portion of the gas supply to inlet means 30 and 32, and location 44 comprises an orificed coupling for joining the gas portion, from outlet means 34 and 36, with inlet line 26.

By this arrangement, this method, the secondary inlet and outlet means 30 and 34, and 32 and 36 are commonly throughconnected with the primary inlet means 18 and 22; after the shunting of a minor portion of the pressured gas to be processed, through the devices 40, said minor portion is reunited with the main gas stream for dehydration therewith in chamber 10 or 12-depending upon the status of the system cycle.

The schematic diagram shows valves 46 and 48 in the secondary inlet means or lines 30 and 32, and valves 50 and 52 in the primary inlet means or lines 18 and 22. The

purpose of these valves is to insure that chamber admits the major portion of the pressured gas to be processed, for purposes of dehydration thereof, while chamber 12 admits the minor portion of said gas for purposes of reactivation of the desiccant medium 38 therewithin. And, of course, the valves are provisioned to accommodate for the alternate processing, when chamber 10 approaches saturation, and requires reactivation, and chamber 12 has been reactivated, and can accept gas for the dehydration thereof.

Finally it will be noted that chambers 10 and 12 have venting inlet and outlet ports; chamber 10 has inlet and outlet ports 54 and 56, and chamber 12 has inlet and outlet ports 58 and 60, respectively. Vacuum pumps 62 are operatively in flow communication with venting outlet ports 56 and 60, to remove from chambers 10 and 12 the aqueous constituents which the desiccant medium 38 in each extracts from the gas.

As is common practice, the output product of the gas compressor 16 is conducted through a cooler 64 interposed in system inlet line 26. Cooler 64 is positioned between locations 42 and 44 to insure that the minor portion of supply gas admitted to devices remains in a heated condition.

In operation, by novel method of gas dehydration, which can be practiced with the inventive apparatus represented, by Way of example, in the diagram of the figure, conducts the major gas stream via inlet line 26 to the chambers 10 or 12. For purposes of explanation, let it be assumed that chamber 10 is in condition to dehydrate process or aqueous-constituent-laden gas, and chamber '12 is near saturation, requiring reactivation. Control means (not shown) which can be manually actuated, or automatically actuated by means programmed by the quantity or timing of gas flow from compressor 16, will have closed valves 46 and 52, and opened valves 48 and 50. Thus, the major gas flow will be conducted through open valve 50, through the absorbent desiccant medium 38 in chamber 10, and conducted out, dehydrated, via system outlet line 28. Meanwhile, a minor portion of the gas flow will be conducted via open valve 48 through the heat exchanger 40, in chamber 12, where it heats the desiccant medium 38 therein. The control means priorly noted are manually or automatically actuated, when the desiccant medium 38 in chamber 12 is sutliciently heated, to operate the vacuum pump 62 associated with outlet port 60. In this manner, ambient, atmospheric 'air is introduced to the medium 38, is heated and expanded, and pulled from the medium 38 by the pump 62 removing the aqueous constituents therefrom. Inlet venting port 58, and port 54 as well, has check valving associated therewith which is normally closed and opened automatically only in response to the operation of pump 62.

When chamber 10 is saturated, the control means-of a type well known and commonly employed in the art to I which this invention pertains-will close valves and 48 and open valves 46 and 52. The control means will also, simultaneously, halt the vacuum pump 62 associated with port when the minor How of gas from compressor 14 which is now conducted to chamber 10- has sufl'iciently heated the desiccant medium 38 therein, the control means will cause the vacuum pump 62 associated with port 56 to operate. The chamber 10 will have removed therefrom the aqueous constituents entrained by the medium 38 therewithin, while chamber 12 is then dehydrating the major portion of the process gas.

My invention is especially useful in dehydration of hot compressed gas from a gas compressor. Accordingly, a gas compressor '16 is represented in the diagrammatic figure as the source of the hot, pressured gas. Any source of hot, pressured gas, however, will be efliciently dehydrated in accordance with my novel method, or with my novel apparatus.

The teaching of my disclosure is the conducting of the major portion of the gas supply through a first aqueous extractor, for dehydration, while a minor portion of the gas supply is conducted through a second aqueous extractor for reactivation of the latter. My teaching requires no diverting of any portion of the dehydrated gas product for purposes of reactivation. All the dehydrated gas is available as an output product. What is more, the minor portion of the gas supply which is used for reactivation is only shunted from the principal stream of gas. After it has been conducted through the heat exchanger devices 40, it is reunited with the principal gas stream. It is joined to the main stream at location 44, and reclaimed for inclusion in the subsequent output product.

While I have described my invention in connection with a specific embodiment thereof, which embodiment can be used to practice the inventive method here taught, it is to be clearly understood that this is done only by way of example and not as a limitation to the scope of my invention as set forth in the objects thereof and in the accompanying claims.

I claim:

1. Apparatus for dehydrating a supply of hot, pressured gas, comprising:

a plurality of means for extracting aqueous constituents from said gas each means of said plurality confining indirect heat exchange means therewithin;

means interposed between the supply of gas and said plurality dividing said gas into minor and major portions;

each of said extracting means having rimary gas inlet and outlet means for admitting the major portion of said gas therethrough for dehydration thereof;

each of said extracting means having secondary gas inlet and outlet means for admitting the minor portion of said gas therethrough for cooperation with said heat exchange means for effecting reactivation of said extracting means; wherein said primary and secondary means include means for controlling the admittance of gas therethrough; and

said secondary inlet and outlet means of each of said extracting means are shuntedly through connected with one of said primary inlet and outlet means thereof, to cause gas admitted via said secondary means both to be taken from said supply and to be joined with gas admitted via said primary means; and further including a single cooler through connected with said primary gas inlet means for causing only the major portion of said gas to be cooled thereby.

2. Apparatus, according to claim 1, wherein:

said plurality of extracting means comprise desiccant chambers.

3. Apparatus, according to claim 1, wherein:

said heat exchange means are interpositioned between, and connected with, said secondary inlet and outlet means.

4. Apparatus, according to claim 1, wherein:

said primary inlet and outlet means are disposed for admitting gas therethrough in a first direction.

5. Apparatus, according to claim 4, wherein:

said secondary inlet and outlet means are disposed for admitting gas therethrough in a second direction.

6. Apparatus, according to claim 1, further including:

venting inlet and outlet ports for admitting a gas which is cooler than said supply gas through said extracting means to remove extracted aqueous constituents therefrom, said ports and such cooler gas admitted therethrough being cooperative with said heat exchange means and said minor portion of said gas to effect reactivation of said extracting means.

7. Apparatus, according to claim 6, wherein:

one of said venting ports has an air-mover device operatively through connected therewith.

8. Apparatus, according to claim 1, wherein:

said controlling means comprise valving means interposed in said inlet means for admitting gas through one of said primary and one of said secondary inlet means and for prohibiting such admittance through any other of said primary and secondary inlet means. 9. A method of dehydrating a supply of hot, pressured gas, comprising the steps of:

joining said minor portion with said major portion for reclamation thereof; and

controlling the admittance of said major and minor portions to said devices; wherein the step of controlling the admittance of said gas portions comprises admitting said major portion to said one device while prohibiting admittance of said major portion to said another device, and admitting said minor portion to said another device while prohibiting admittance of said minor portion to said one device.

10. A method, according to claim 9, further including he step of:

conducting a gas which is cooler than said supply gas through said devices for effecting the removal of extracted aqueous constituents from said devices and to cooperate with the minor gas portion and the heat exchange means thereby to reactivate said devices.

11. In a compressed gas drying system including a ing material adapted to absorb moisture from a gas on contact and to release said moisture upon being heated;

each of said chambers also containing a passage adapted to convey a heating fluid through said moistureabsorbing material for heating purposes;

means for admitting the cooled compressed gas received from said cooler selectively and alternately to each of said chambers for drying said gas;

other means for selectively and alternately conveying a portion of the gas, in a shunted avoidance of the cooler, to each of said heating fluid passages; and

further means for joining all the gas from each of said heating fluid passages with said cooled gas prior to admission of said cooled gas to one of said chambers.

References Cited UNITED STATES PATENTS 1,948,779 2/1934 Abbott et al. 55-62X 2,071,868 2/1937 Von Lube 55-33 FOREIGN PATENTS 449,952 7/1948 Canada 55-33 871,191 3/1953 Germany 55-62 JOHN ADEE, Primary Examiner US. Cl. X.R. 

